This invention generally relates to microelectromechanical (MEM) devices. More particularly, it relates to immobilization during assembly and sealing during operation of a MEMS device to prevent damage and contamination during manufacture, particularly for use as a micro-actuator in a hard disk drive.
Microelectromechanical systems are integrated micro devices or systems combining electrical and mechanical components fabricated in the similar processes to those used in the fabrication of standard integrated circuit devices.
However, unlike standard integrated circuits which process electronic signals, microelectromechanical systems are designed to generate electronic signals by their ability to undergo physical deformation or motion in response to external physical stimuli such as acceleration, external atmospheric pressure or temperature, and acoustic waves.
Other microelectromechanical systems are now being introduced that provide mechanical movement in response to electrical stimulation. In particular, Microelectromechanical systems have been introduced to provide a micro-actuator for hard disk drive systems.
Due to their small size MEM structures may be fragile subsequent to manufacture and need protection during processing and system integration. The present invention describes a method and structure for protecting a MEM device during the manufacturing process and sealing the device against contamination during the use of the device.
In one embodiment of the invention, a MEM device is immobilized by placing a material over the gap between movable structures that can be made stiff during manufacture and then flexible after the manufacturing process is complete. A preferable material is expanded PTFE (ePTFE) that can be made stiff with a material that can later be dissolved and removed to leave a filter like cover over the gap in the MEM device.
An advantage of the present invention is immobilization material can be used as a filter or isolation membrane during the MEM devices actual operation mode to prevent contamination between the small gaps of the moving parts.
An additional advantage of the present invention is the expanded PTFE can be bonded to the MEM device by selective application of adhesive or by metallurgical attachment between metal on the MEM device and metal embedded in the ePTFE. This ability to vary the method of attaching the ePTFE enables the present invention to be adapted for use with expected variations of MEM devices for a variety of applications.
Another advantage of the present invention is the ePTFE material that bridges the gap between movable portions of the MEM device can be used to make electrical interconnects across the gap. Also, input and output connection points can be fabricated on the top surface, the bottom surface or through the web of the ePTFE material. These interconnects and connection points may be formed by a selective application of conductive material in both the X/Y as well as the Z-axis of the ePTFE material.